Police said the “savage and brutal” attack on Jordan Watson had shocked officers working on the case in Carlisle, Cumbria.
Jordan’s body was discovered by a member of the public in the grounds of St John the Baptist CE Church cemetery on Tuesday morning.
A post-mortem examination showed the teenager, from nearby Ridley Road, died from multiple wounds to the head and neck caused by a sharp implement.
The murder suspect, from Carlisle – said to be known to Jordan – was arrested yesterday morning.
Jordan was last seen at a friend’s address nearby at 11pm on Monday before his body was spotted in a secluded part of the cemetery at 7:45am the following day.
The murder weapon has yet to be found as police cordoned off the cemetery and continued extensive searches in the surrounding area.
Senior investigating officer Andrew Slattery, from Cumbria Constabulary, said yesterday’s arrest was “one line of inquiry” as he appealed for more information from the public.
He said: “The investigation is ongoing and we are keeping an open mind about the motive and why indeed this crime took place.
“We would like to hear from anybody who has any information that can assist the investigation in any way. In particular, anybody who saw or heard anything unusual in the area of the cemetery or anybody who saw Jordan on the 15th of June.”
Jordan, who had a slim build and brown hair, was last seen wearing a blue and grey hoodie, black Adidas T-shirt, grey tracksuit bottoms and grey Nike trainers.
Family liaison officers are supporting the teenager’s family.
Friends paid tribute to the keen Liverpool FC supporter as a “kind-hearted boy”, while his headteacher at the Gillford Centre in Carlisle said 5ft Jordan was “small in stature but big on personality”.
Lauren Blakey, 16, said the youngster “did not deserve to die” as she laid a floral tribute outside the cemetery. She said: “He was such a kind-hearted boy. I can’t believe it.
“I just keep thinking he is going to come round the corner, bouncing and lively. Everyone loved him. He was easy to get on with. You don’t expect this sort of thing to happen in Carlisle. He did not to deserve to die.”
Speaking at a press conference in Carlisle, Assistant Chief Constable Darren Martland said: “Our thoughts are very much with Jordan’s family at this tragic time. We are also very much acutely aware of the impact and the nature of Jordan’s death, and the anxiety and concerns that may be expressed by the local community.
“On behalf of Cumbria Constabulary, I would like to reassure the communities in Cumbria that we will do everything, working with those communities and our partners, to identify the individual or people responsible for Jordan’s death and bring them to justice.”